Some patients receive an implantable medical device (IMD), such as a pacemaker, that is capable of applying pacing stimuli to the left ventricle of the heart, or to the right ventricle, or to both ventricles. Pacing both ventricles during a cardiac cycle, a technique known as “bi-ventricular pacing,” may be useful for treating inter—and/or intraventricular electrical-mechanical dysynchrony. In some patients, however, pacing the left ventricle alone may be as beneficial as bi-ventricular pacing, or perhaps more beneficial than bi-ventricular pacing.
When a patient first receives an IMD that can perform bi-ventricular pacing, the physician for the patient typically enables bi-ventricular pacing, causing the IMD to pace both ventricles. Bi-ventricular pacing is often seen as a safety measure. In the event of failure or dislodgement of the left ventricular pacing lead, pacing only the left ventricle may result in a failure of pacing to “capture” the ventricles, i.e., to cause the ventricles to activate. Left ventricular pacing that fails to activate the ventricles does not help the patient. Because of considerations such as these, physicians are hesitant to rely on left ventricular pacing, and may program the IMD to apply bi-ventricular pacing.